This grant addresses the role of autologous bone marrow transplantation in acute leukemia, myeloma and diffuse large cell lymphoma when combined with high-dose chemotherapy and total body irradiation. As these are bone marrow based diseases, the question of purging to remove malignant cells before transplantation is evident. Two new separation procedures have been developed, in vitro immunocolloid separation and pharmacological tumor cell reduction. We propose to study the effect of the separation technique on hematopoietic reconstruction capacity and the efficacy of each separation as measured by time to tumor recurrence. Detection systems for leukemic cells have been developed using molecular probes and will be applied for monitoring bone marrow for leukemic cell contamination according to method of purging. Well defined tumor markers will be employed in transplants in myeloma.